In the disk drive unit industry today, different methods are used to support a slider with magnetic head to selectively read from and write to a rotating disk, one of which is called CSS (contact start stop), and the other is called load/unload, both kinds of the methods are related with a support structure or design of a suspension of a HGA in the disk drive unit.
FIGS. 1a-1c illustrate a conventional HGA that includes a slider 106′, incorporating a magnetic read/write head, and a suspension 101′. The suspension 101′ includes a load beam 102′, a flexure 103′, and a base plate 105′, all of which are assembled together. The flexure 103′ provides a suspension tongue 104′ for supporting the slider 106′ thereon. A dimple 107′ is formed on a distal end of the load beam 102′ to support the suspension tongue 104 of the flexure 103′ at a position corresponding to a center of the slider 106′, thereby transferring load forces from the load beam 102′ to the slider 106′. The top of the dimple 107′ is cone-shaped, so the flexure 103′ can rotate freely around top end of the dimple 107′, and the slider 106′ mounted on the suspension tongue 104′ of the flexure 103′, thus the slider 106′ can rotate along with the suspension tongue 104′.
However, such a dimple is required to use a punch coining die or a pulsed laser energy treatment to manufacture, so the manufacturing processes are rather complicated and easy to cause the dimple geometry asymmetric. Once the dimple is geometry asymmetric, the load beam 102′ and the flexure 103′ may be misaligned with each other, and the dimple 107′ may not match the center of the slider 106′ so as not to transfer the loading force to the center of the slider 106′, which will cause unbalance of the movement of the slider 106′ and, in turn, affect the slider 106′ flying stability. Moreover, even if the geometry of the dimple 107′ is symmetric, as there is no special positioning mechanism, it is difficult to align the load beam 102′ with the flexure 103′ in assembly.
In additional, the conventional HGA has a drawback in shock performance. As illustrated in FIGS. 2a and 2b, since the slider 106′ and the flexure 103′ are supported by the dimple 107′ only and the other region is free, the suspension tongue 104′ of the flexure 103′ and the dimple 107′ are easy to separate when a shock or a vibration event happens. Even a limiter is provided to the suspension 101′ to reduce the movement of the flexure 103′, but the movement can not be avoided because the clearance of the limiter gap is difficult to control.
Furthermore, a dimple contact force (DCF) between the dimple 107′ and the flexure 103′ is a very important parameter to keep a good characteristic of the HGA. Due to the DCF is very small (Normal DCF is 2-4 g for 30% slider and 0.1-0.3 g for 20% slider), it is difficult to test and control the DCF especially for the small size slider (such as 20%, 15%, or 10% slider).
Meanwhile, during the operation of the disk drive unit and the high-speed rotation of the slider 106′, the temperature of the slider 106′ increases quickly, and the slider 106′ endures a profile deformation against the temperature change. The profile deformation, especially the air bearing surface (ABS) profile deformation, affects the slider 106′ flying height and stability. FIG. 5a is a graph to show a curve between crown of a slider 106′ against temperature. It can be seen from FIG. 5a that the crown change is quite big. This is because the slider 106′ in the conventional HGA is fully mounted on the suspension tongue 104′ and the heat generated between the slider 106′ and the suspension tongue 104′ is not easy to be emitted. This will seriously affect the flying height characteristic and the flying stability of the slider 106′.
Therefore, there is a need for an improved head suspension assembly and a disk drive unit to overcome these above-mentioned disadvantages.